"A Widely Tunable Laser Based on Multiple Etched Slots"

John F Donegan, CRANN Nanoscience Institute, Trinity College Dublin

May 24th (Monday), 2:00pm
ESB 2001

We, along with researchers in the Tyndall National Institute, have developed a novel multi-section widely tunable laser that has strong potential to be used in a monolithically integrated source. In the talk, we will concentrate on a three-section device, with a central gain section and two mirrors section at front and back. The fabrication is inherently simple and goes not require re-growth. The ridge and slots are created at the same time and in this design, the slot depth is the same as the ridge. The slot spacing is chosen to produce a 400 GHz channel spacing and Vernier tuning is realised through slightly different slot widths in the front and back mirror sections. The laser design we use is all active, in that the mirror sections are part of the laser structure. The slots introduce the needed reflection to achieve lasing but also introduce loss. The loss is overcome by the inclusion of the mirror sections in the laser structure. A key point in this device is that the reflection from a set of slots is sufficient to achieve lasing without the need for cleaved ends on the device. This is a necessity to ensure that the device can be integrated with semiconductor optical amplifiers and Mach-Zehnder modulators. Measurements of the tuning characteristics of these lasers, their linewidths and the switching speed between channels will be presented.

* Discretely Tunable Semiconductor Lasers Suitable for Photonic Integration IEEE Journal of Selected Topics in Quantum Electronics 15 (2009) 482-487 [Wei-Hua Guo, Peter Engelstaedter, Diarmuid Byrne, Qia-Oyin Lu, Brian Corbett, Brendan Roycroft, Frank H. Peters, John F. Donegan]

About John F Donegan:

John F. Donegan is Professor of Physics and Principal Investigator in the CRANN Nanoscience Institute in Trinity College Dublin. He is presently the Head of the School of Physics. Having completed his PhD in University College Galway, he spent sabbatical periods in Lehigh University and in the Max Planck Institut für Festkörperforschung, Stuttgart, Germany. He has been in Trinity College Dublin since 1990. In his research he deals with optically guided structures such as lasers, waveguides and microcavities. He has published over 200 papers in these areas and has 10 patents.

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